In regions where the air temperature remains below freezing for substantial periods of time, it is difficult to maintain free access to a water source which is frozen on its surface. In particular, in the practice of ice fishing, it is common for a fisherman to bore a hole in the frozen lake surface in the beginning of the fishing season and return to that same boring throughout the course of the winter. Since it is essentially impossible to prevent the access hole from refreezing without the constant application of energy, a new hole must be bored through the ice frequently.
As an alternative to boring new holes, means may be provided for reopening the access hole by removing the ice plug which forms therein. In my U.S. Pat. No. 3,059,451, I describe a device for removing the ice block which forms in the access hole. Other such devices such as that shown in the Meagher U.S. Pat. No. 2,799,146, provide solutions to this problem.
Although many of these prior art devices satisfactorily reopen the access hole, the device itself often becomes firmly frozen into place and cannot be removed without damage thereto. Furthermore, many of these devices are either heavier than water and therefore may sink to the bottom of the lake, or much lighter than water and will not stay positioned partially immersed in the body of water.
The present invention provides solutions to problems encountered in the prior art devices by providing means for removing the device after use and, in one embodiment, by adjustment of the buoyancy so as to make positioning of the device easy.